The invention relates to the use of glycidyl ether-capped acetylenic diol ethoxylates, their manufacture, and their use to reduce surface tension in water-based systems.
The ability to reduce the surface tension of water is of great importance in the application of waterborne formulations because decreased surface tension translates to enhanced substrate wetting. Examples of such waterborne compositions include coatings, inks, adhesives, fountain solutions, cleaning compositions and agricultural formulations. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants, resulting in enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension performance is important when the system is at rest. Dynamic surface tension provides a measure of the ability of a surfactant to reduce surface tension and provide wetting under high speed application conditions, i.e., high surface creation rates.
Surfactants based on acetylenic glycols such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol (1) and its ethoxylates (2) are known for their good balance of equilibrium and dynamic surface-tension-reducing capabilities with few of the negative features of traditional nonionic and anionic surfactants. 
Relative to other families of nonionic surfactants, however, these materials have high critical micelle concentrations, making them less efficient in emulsification and solubilization processes. Acetylenic diols and their ethoxylates are relatively inefficient with respect to surface tension reduction, requiring higher use levels to obtain an equivalent reduction in surface tension. They also have limitations with respect to their effectiveness, that is their ability to reduce the surface tension of a formulation to a low value, regardless of the amount of surfactant used. Finally, acetylenic diol ethoxylates are relatively low foam surfactants, and in many applications, for example cleaning formulations, the formation of foam is desirable from both a performance and aesthetic standpoint.
The importance of a surfactant achieving efficient emulsification and solubilization, and low surface tensions at low use levels, and the ability to control the foam characteristics of a surfactant are of considerable industrial importance and are well appreciated in the art. Extensive discussions of the fundamental properties and practical application of surfactants can be found in Rosen, Surfactants and Interfacial Phenomena, Second Edition and in Kirk Othmer Encyclopedia of Chemical Technology, Fourth Edition, Volume 23, pp 477-541, which are incorporated by reference.
Many surfactants have the ability to emulsify or solubilize otherwise insoluble organic materials in aqueous media. This emulsification or solubilization generally occurs only at concentrations higher than the critical micelle concentration. It is therefore desirable that surfactants have low critical micelle concentrations, because this will lead to more efficient surfactant utilization [Rosen, p 171ff]. Low critical micelle concentrations are also desirable because they lead to diminished skin and eye irritation.
The ability of a surfactant to reduce the surface tension of an aqueous formulation is important in promoting substrate wetting. Two parameters which are important when evaluating the relative ability of a surfactant to provide surface tension reduction are the efficiency and effectiveness of the surfactant. The efficiency of a surfactant can be defined by its pC20 value:
pC20=xe2x88x92log C20
where C20 is the concentration in moles/liter of surfactant required to reduce the surface tension of water by 20 dynes/cm. pC20 provides a means for comparison of the relative amount of surfactant required to obtain a given surface tension reduction. Since the scale is logarithmic, an increase in pC20 value of 1 corresponds to a decrease by a factor of 10 in the amount of surfactant required to provide a given surface tension reduction.
The effectiveness of a surfactant can be defined by its limiting surface tension (limiting xcex3) which is the minimum surface tension observed for an aqueous solution of the surfactant, regardless of surfactant concentration. Effective surfactants can provide wetting under challenging conditions such as those presented by low energy or contaminated substrates.
The foaming characteristics of a surfactant are important because they can help define applications for which the surfactant might be suitable. For example, foam can be desirable for applications such as ore flotation and cleaning. On the other hand, in coatings, graphic arts and adhesive applications, foam is undesirable because it can complicate application and lead to defect formation.
There are numerous references that disclose alkoxylated acetylenic diols and their uses including: U.S. Pat. Nos. 3,268,593; 4,117,249; 5,650,543; 6,313,182; JP 2636954 B2; JP 2621662 B2; JP 04071894 A; JP 2569377 B2; JP 09150577 A; JP 04091168 A; JP 06279081 A; JP 03063187 A; JP 2000144026 A and Leeds, M. W.; Tedeschi, R. J.; Dumovich, S. J. Casey, A. W. IandEC Product Research and Development 1965, 4, 237.
This invention provides glycidyl ether-capped acetylenic diol ethoxylates which act as surfactants for water-based compositions. The glycidyl ether-capped acetylenic diol ethoxylates have the structure: 
wherein:
R1 is hydrogen or a linear, branched, or cyclic alkyl group having from 1 to about 6 carbon atoms;
R2 is a linear, branched, or cyclic alkyl group having from 1 to about 12 carbon atoms;
R3=xe2x80x94CH2OR4;
R4 is a linear, branched, or cyclic alkyl, alkenyl, aryl, or aralkyl group having from 2 to about 30 carbon atoms;
(n+m) is an average value from about 1 to about 100; and
(p+q) is an average value from about 0.5 to about 5.
This invention also relates to processes for the manufacture of glycidyl ether-capped acetylenic diol ethoxylates.
Another embodiment of the invention affords water-based compositions containing an organic or inorganic compound, particularly aqueous organic coating, ink, and agricultural compositions, having reduced equilibrium and dynamic surface tension by incorporation of an effective amount of a glycidyl ether-capped acetylenic diol ethoxylates of the above structure.
It is desirable that an aqueous solution of the glycidyl ether-capped acetylenic diol ethoxylates demonstrates a dynamic surface tension of less than 35 dynes/cm at a concentration of xe2x89xa60.5 wt % in water at 23xc2x0 C. and 1 bubble/second according to the maximum bubble pressure method. The maximum bubble pressure method of measuring surface tension is described in Langmuir 1986, 2, 428-432, which is incorporated by reference.
Also provided is a method for lowering the equilibrium and dynamic surface tension of aqueous compositions by the incorporation of these glycidyl ether-capped acetylenic diol ethoxylate compounds.
Also provided is a method for applying a water-based inorganic or organic compound containing composition to a surface to partially or fully coat the surface with the water-based composition, the composition containing an effective amount of a glycidyl ether-capped acetylenic diol ethoxylate compound of the above structure for reducing the dynamic surface tension of the water-based composition.
There are significant advantages associated with the use of these glycidyl ether-capped acetylenic diol ethoxylates in water-based organic coatings, inks, fountain solutions for gravure printing processes, and agricultural compositions and these advantages include: an ability to formulate water-borne compositions which may be applied to a variety of substrates with excellent wetting of substrate surfaces including contaminated and low energy surfaces; an ability to provide a reduction in coating or printing defects such as orange peel and flow/leveling deficiencies; an ability to produce water-borne coatings, fountain solutions and inks which have low volatile organic content, thus making these glycidyl ether-capped acetylenic diol ethoxylate surfactants environmentally favorable; an ability to formulate coating, fountain solution and ink compositions capable of high speed application; and an ability to control the foaming characteristics of the water-based compositions.
Because of their excellent surfactant properties and the ability to control foam, these materials are likely to find use in many applications in which reduction in dynamic and equilibrium surface tension and low foam are important. Such uses include various wet-processing textile operations, such as dyeing of fibers, fiber scouring, and kier boiling, where low-foaming properties would be particularly advantageous. They may also have applicability in soaps, water-based perfumes, shampoos, and various detergents.
A preferred embodiment of the invention comprises an acid gas scrubbing process for the removal of acid gases, i.e., hydrogen sulfide and/or carbon dioxide, from an acid gas-containing gas stream, such as natural and petroleum gases. The acid gas scrubbing, or sweetening, comprises contacting the acid gas-containing gas stream with an aqueous amine solution to adsorb the hydrogen sulfide and/or carbon dioxide, optionally regenerating the aqueous amine solution, and adding a glycidyl ether-capped acetylenic diol ethoxylate according to the invention.
This invention relates to acetylenic diol ethoxylates capped with hydrophobic glycidyl ethers, their manufacture, and their use to reduce the surface tension in water-based systems. The novel derivatives of this invention are prepared by reaction of an acetylenic diol ethoxylate with a suitable oxirane-containing compound. The reaction product can be represented by the following structure 
wherein:
R1 is hydrogen or a linear, branched, or cyclic alkyl group having from 1 to about 6 carbon atoms;
R2 is a linear, branched, or cyclic alkyl group having from 1 to about 12 carbon atoms;
R3=xe2x80x94CH2OR4;
R4 is a linear, branched, or cyclic alkyl, alkenyl, aryl, or aralkyl group having from 2 to about 30 carbon atoms;
(n+m) is an average value from about 1 to about 100; and
(p+q) is an average value from about 0.5 to about 5.
As is well-known, a mixture of isomers will generally be formed because reaction of the ethoxylate with the oxirane-containing material can occur on either an internal carbon or terminal carbon. The selectivity to each isomer will be influenced by the type of catalyst used and the reaction conditions. Thus in many instances a significant, or even major, portion of the reaction product may be comprised of the following isomers: 
where the R groups have the designations above and the isomeric composition of the p- and q-length oligomeric chains may of course be mixed.
The products are prepared by ethoxylation of an acetylenic diol of the form: 
where R1 and R2 are defined as above, followed by adduction with a suitable oxirane-containing material. The preferred acetylenic starting materials are those in which R1 is methyl and R2 is a linear, branched, or cyclic alkyl group having from 3 to about 6 carbon atoms. More preferred acetylenic starting materials are those in which R1 is methyl and R2 is a linear, branched, or cyclic alkyl group having from 4 to 5 carbon atoms, and most preferably R2 is isobutyl or isoamyl.
The amount of ethylene oxide used to prepare the ethoxylated intermediates can vary from 1 mole to about 100 moles. Preferred derivatives will contain from about 1.3 to about 50 moles of ethylene oxide. Most preferred derivatives will contain from about 10 to about 30 moles of ethylene oxide.
Any glycidyl ether, i.e. material of the formula 
is suitable for use as a capping agent. The amount of glycidyl ether should be from about 0.5 to 5 moles based upon starting acetylenic diol ethoxylate, preferably 1 to 3 moles, and most preferably about 2 moles. The R4 substituent on the glycidyl ether can be a linear, branched, or cyclic alkyl, alkenyl, aryl, or aralkyl group having from 2 to about 30 carbon atoms. Preferably, the R4 substituent is a linear, branched, or cyclic alkyl, alkenyl, aryl, or aralkyl group having from 3 to about 20 carbon atoms, more preferably the R4 substituent has from 4 to about 12 carbon atoms. Examples of suitable glycidyl ethers include ethyl glycidyl ether, butyl glycidyl ether, hexyl glycidyl ether, octyl glycidyl ether, 2-ethylhexyl glycidyl ether, dodecyl glycidyl ether, octadecyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, and the like. Most especially preferred derivatives are those from butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and dodecyl glycidyl ether.
As set out above, (n+m) is from 1 to about 100. Preferably, (n+m) is from 1.3 to about 50, more preferably (n+m) is from 10 to about 30, and most preferably (n+m) is 10. As set out above, (p+q) is from 0.5 to about 5. Preferably, (p+q) is from about 1 to about 3, and most preferably (p+q) is 2.
To prepare the adducts of the invention, acetylenic diol ethoxylates are adducted with the glycidyl ether in the presence of a suitable catalyst at a temperature sufficiently high so as to provide a convenient reaction rate, and low enough to prevent significant byproduct formation. Reaction temperatures range from about 40 to about 150xc2x0 C., preferably 50-130xc2x0 C., and most preferably 60-120xc2x0 C., although optimal reaction temperatures will depend on the choice of catalyst, reactor configuration, and other variables. The acetylenic diol ethoxylate may be preformed or be made in situ using conventional procedures as disclosed in U.S. Pat. No. 6,313,182 B1. The capping reaction may be performed in the presence of basic catalysts such as alkali metal or alkaline earth hydroxides and tertiary amines, or in the presence of Lewis or Bronsted acid catalysts. Examples of alkali metal and alkaline earth hydroxides include materials such as LiOH, NaOH, KOH, CsOH, FrOH, Be(OH)2, Mg(OH)2, Ca(OH)2, Sr(OH)2 and so on. For commercial production, KOH and NaOH are preferred. Suitable tertiary amine catalysts include trimethylamine, dimethylethylamine, N-methyl-piperidine, pyridine, 4-(N,N-dimethylamino)-pyridine, N,Nxe2x80x2-dimethylpiperazine, quinuclidine, 1,4-diazabicyclo[2.2.2]octane, and the like. Trimethylamine is preferred. Examples of Lewis acid catalysts include BCl3, AlCl3, TiCl4, BF3, SnCl4, ZnCl2 and the like. The preferred Lewis acid catalyst is BF3. A sufficient amount of catalyst should be used to provide a convenient reaction rate, but not so much as to impact product purity or complicate post treatment.
When adding glycidyl ethers to the acetylenic glycol and the catalyst, care should be taken to avoid the presence of an excess of unreacted glycidyl ether in the reaction mixture since the reaction is very exothermic and could prove to be very hazardous. The danger of an uncontrollable reaction can be avoided by adding the glycidyl ether in a manner and at a rate such that it reacts as rapidly as it is introduced into the reaction mixture.
The performance properties of these products may be optimized for a specific application by appropriate modification of the alkyl substituents R1 and R2, the degree of ethoxylation (n+m), the degree of adduction (p+q), and the choice of group used as an end cap. The interplay between these factors appears to be complex and is not well-understood. However, it is clear that manipulation of these variables allows access to materials which can perform as emulsifiers or detergents, wetting agents, foaming agents, defoamers, rheology modifiers or associative thickeners, dispersants, and the like. As such, these products will be useful in applications such as coatings, inks, adhesives, agricultural formulations, fountain solutions, photoresist strippers/developers, soaps, shampoos, and other cleaning compositions. They should also find use in oil-field applications such as enhanced oil recovery, fracturing and stimulation processes, and drilling and cementing operations, and in various wet-processing textile operations, such as dyeing of fibers, fiber scouring and kier boiling, and so on.
In another embodiment, the invention relates to an aqueous composition comprising in water an inorganic compound which is a mineral ore or a pigment or an organic compound which is a pigment, a polymerizable monomer, an oligomeric resin, a polymeric resin, a detergent, a herbicide, an insecticide, or a plant growth modifying agent and an effective amount of a glycidyl ether-capped acetylenic diol ethoxylate for reducing the dynamic surface tension of the composition, the glycidyl ether-capped acetylenic diol ethoxylate having a structure according to the formula: 
wherein R1, R2, R3, R4, n, m, p, and q are as defined above.
A typical water-based coating composition to which the surfactants of the invention may be added may comprise the following components in an aqueous medium at 30 to 80 wt % solids:
(a) 0 to 50 wt % of a pigment dispersant/grind resin;
(b) 0 to 80 wt % of coloring pigments/extender pigments/anti-corrosive pigments/other pigment types;
(c) 5 to 94.98 wt % of a water-borne/water-dispersible/water-soluble resin;
(d) 0 to 30 wt % of slip additives/antimicrobials/processing aids/defoamers;
(e) 0 to 50 wt % of coalescing or other solvents;
(f) 0.01 to 10 wt % of surfactant/wetting agent/flow and leveling agents; and
(g) 0.01 to 5 wt % of a glycidyl ether-capped acetylenic diol ethoxylate.
A typical water-based ink composition to which the surfactants of the invention may be added comprise the following components in an aqueous medium at 20 to 60 % solids:
(a) 1 to 50 wt % of a pigment;
(b) 0 to 50 wt % of a pigment dispersant/grind resin;
(c) 0 to 50 wt % of a clay base in appropriate resin solution vehicle;
(d) 5 to 93.97 wt % of a water-borne/water-dispersible/water-soluble resin;
(e) 0 to 30 wt % of coalescing solvents;
(f) 0.01 to 10 wt % of a surfactant/wetting agent;
(g) 0.01 to 10 wt % of processing aids/defoamers/solubilizing agents; and
(h) 0.01 to 5 wt % of a glycidyl ether-capped acetylenic diol ethoxylate.
A typical water-based agricultural composition to which the surfactants of the invention may be added may comprise the following components in an aqueous medium at 0.01 to 80 wt % solids:
(a) 0.1 to 50 wt % of a pesticide or plant growth modifying agent;
(b) 0.01 to 10 wt % of a surfactant;
(c) 0 to 5 wt % of dyes;
(d) 0 to 20 wt % of thickeners/stabilizers/co-surfactants/gel inhibitors/defoamers;
(e) 0 to 25 wt % of antifreeze; and
(f) 0.01 to 50 wt % of a glycidyl ether-capped acetylenic diol ethoxylate.
A typical fountain solution composition for planographic printing to which the surfactants of the invention may be added would comprise the following components:
(a) 0.05 to 10 wt % of a film formable, water soluble macromolecule;
(b) 1 to 25 wt % of an alcohol, glycol, or polyol with 2-12 carbon atoms, water soluble or can be made to be water soluble;
(c) 0.01 to 20 wt % of a water soluble organic acid, inorganic acid, or a salt thereof;
(d) 30 to 70 wt % of water; and
(e) 0.01 to 5 wt % of a glycidyl ether-capped acetylenic diol ethoxylate.
A typical water-based photoresist developer or electronic cleaning composition to which the foam controlling agent of the invention may be added would comprise the following components:
(a) 0.1 to 3 wt % tetramethylammonium hydroxide;
(b) 0 to 4 wt % phenolic resin;
(c) 88 to 99.99 wt % water; and
(d) 10-50,000 ppm glycidyl ether-capped acetylenic diol ethoxylate.
A typical acid gas scrubbing composition would comprise in water 10 to 70 wt % of at least one amine, preferably alkanolamine, as is well known in the art and 1 to 500 ppm of a glycidyl ether-capped acetylenic diol ethoxylate.
The present invention can be further illustrated by the following examples of preferred embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention unless otherwise specifically indicated.